Medical practitioners, such as military medics, civilian emergency-medical personnel, nurses, and physicians, routinely perform vascular-access procedures (e.g., IV insertion, central venous-line placement, peripherally-inserted central catheter, etc). It is desirable for a practitioner to be proficient at performing these procedures since the proficient practitioner is far less likely to injure a patient and is almost certain to reduce the patient's level of discomfort.
Becoming proficient in vascular-access procedures requires practice. In fact, the certification and re-certification requirements of some states mandate a minimal number of needle sticks, etc., per year per provider. Historically, medical practitioners practiced needle-based procedures on live volunteers. More recently, simulation techniques and devices have been developed to provide training in vascular-access procedures without the use of live volunteers. U.S. Pat. No. 6,470,302 (“the '302 patent”) surveys the art of medical-simulation devices and also discloses a vascular-access simulation system.
The vascular-access simulation system that is disclosed in the '302 patent includes an “interface” device and a computer system. To practice a vascular-access procedure, a user manipulates an “instrument,” referred to in the patent as a “catheter unit assembly,” which extends from the device and serves as a catheter-needle. Potentiometers and encoders within the interface device track the motion and position of the instrument and relay this information to the computer system. The computer system performs a simulation of the surface and subsurface anatomy of human skin, and determines the effect of the instrument's motion on the skin's anatomy. Simulated results are displayed by the computer system. Using the motion information from the interface device, the computer system also generates a control signal that controls a force-feedback system that is coupled to the instrument. The force-feedback system generates various resistive or reactive forces that are intended to simulate the forces that are experienced by a medical practitioner during an actual vascular-access procedure. The user senses these forces during manipulation of the instrument.
The simulation system that is disclosed in the '302 patent has many shortcomings that substantially limit its utility as a training or accreditation tool. One shortcoming of that simulation system relates to ergonomics.
In particular, when manipulating the catheter-unit assembly of that system, a user's hands are in an awkward and unrealistic position (as compared to the position of the hands during an actual vascular access procedure). This is due, among other reasons, to the height of the interface device, which is a consequence of the layout and design of the mechanisms that compose the interface device.
Furthermore, the relative positioning and arrangement of mechanisms with which a user of that system interacts to practice a vascular access procedure is not ergonomic. Specifically, the simulation system enables a user to perform needle “insertion” as well as a “skin-stretch” technique. The skin stretch normally accompanies catheter insertion during an actual procedure to reduce a patient's level of discomfort and to anchor the vein that is being entered.
In the system that is disclosed in the '302 patent, the skin-stretch mechanism, which includes a belt—a mock skin—, resides within a casing that is attached to and separate from the housing in which the needle-insertion procedure is practiced. To simulate the skin-stretch technique, a user “stretches” the mock skin. In comparison with an actual procedure, the location at which a user stretches the mock skin is rather remote from the needle “insertion point.” Furthermore, the surface of the mock skin is not co-planar with or at the same height as the needle insertion point. In an actual procedure, of course, they are (i.e., the skin surface is the insertion point). This structural arrangement does nothing to promote a user's “suspension of disbelief” and does not provide a particularly realistic simulation.
The inability of prior-art vascular-access simulation systems to realistically simulate a vascular-access procedure limits their usefulness as a training or accreditation tool.